Accomplishment 1: We have designed and built a spectrally revolved fiber photometry system for simultaneous multicomponent analysis of neural activity in freely moving animals. The system can accommodate two (or more) excitation wavelengths (e.g. 488 nm and 561 nm lasers) for simultaneously exciting green and red fluorescent sensors. The system is able to detect fluorescent transients of genetically encoded calcium sensor GCaMP6f in molecularly defined groups of cells in the striatum. The absence of fluorescence transients of the concurrently expressed red fluorescent protein tdTomato suggests that the GCaMP6f transients are the result of neural activity, not movement-induced artifacts. The total cost of the new system is significantly less (50%) than previous systems and the nearly plug-and-play easy assembling steps make this new system a very affordable and applicable system for in vivo neurobehavioral studies. Accomplishment 2: We have designed and built a dual-purpose optical system for both GRIN lens-based fluorescence imaging and high density fiber array photometry in freely moving animals. In the imaging mode, the system can revolve individual neurons expressing fluorescent proteins through an imaging fiber bundle and a 350 micrometer or 500 micrometer OD GRIN lens. The system can be easily converted into a 12 channel (with spectral information) or 48 channel (without spectral information) fiber array photometry system for simultaneous multi-site recordings in less than 15 min.